SELECT 
  1 
FROM 
  cscart_june_setuplock_keys 
WHERE 
  key_id = 'a797048cd7f2c3858cc4783e1f8eccc3750f16ed2bd2b688822fea58c2dc2a46' 
  AND token = '4ln7wtt/iqemyKwXxkOB06r8n9pDj4nkdGnUtEvxaIg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}